I'm sort of new to U/C but have many years in comp FF and RC sailplane, so stopwatches have been a concern.
I like using a wristwatch stopwatch. It's always with you and out of the way. I worry about a watch on a lanyard swinging into the prop.
My favorite is like the Casio DB360 series. It has two large buttons below the face and through the years, using it has become second nature. You should be aware that that the logic between say Casio, Timex and others varies and so once you pick a brand, switching can be a relearning process. Ex- Casio, rt button is start/stop, left is split/reset. Timex is different. I do recommend that you buy the watch in person so you can feel the touch. The Casios vary from model to model. Some are very light in touch and I avoid them.
Al Rabe mentions the wrist band problem. You can get these with a stainless steel band and I have moved the band from watch to watch. BTW the cases don't last forever either but they're cheap!
When checking lap times while flying, I remove the watch and stick it in my pocket since I can't use both hands.
For a dedicated stopwatch, my fav is a Seiko 321. It has a neat countdown (or up) feature but has become ridiculous in price. Casio also makes a very good stand alone stop watch.
Norm's 2 cents